Thermostat.



J. H. SWAN.

THERMOSTAT.

APPLICATION FILED JUNE 15, 1905.

Patented May 11, 1909.

- thermostat for closing" an electric circuit,

' statand to remain closed, until otherwise tions of the thefmostat; to. provide means 2- ofa' radiator, together with a controlling thermostat constructedaccording to my invention; The valve operating mechanism 1904, e'iial' No. 189,928.

: of the valve stem 4. The valve is normally urged to an open position by means of the springs 5. Thedlaphragm is inclosed in a casing 6 and said casing communicatesat its upper end with a steam pressure device.

zen of the United States of America, and a resident of Chicago, in the county of Cook .new and usefulImprovements in T'hermo-j provide an improved form of electric switch .Furt er ob ects'of this Invention are to provide means whereby at the time that the current in said cirpuit will be reduc edbelow' I accomplish theseobjects by the. device.

is not broadly claimed in this application ordinary globe valve arranged to be oper-' 5Q ated by means of a diaphragm 2. The dia- UNrrEi);STATES/PATENT oFFIo-EB JOHN H..-SWAN, OF ciiroAeo, rumors.-

, rnn'nmosra'r.

To'all whom it may concern: e

Be'it known that I, JOHN H. SWAN, a citiand State of Illinois, have invented certain stats, of which the following is a specification. 1

This invention relates to electrical thermostats.

The main objects of thls invent on are to adapted to operate in conjunction with a said switchbeing adapted to res on'dto an extremely. delicate contact-"at t e thermoreleased, regardless o subsequent fluctua-i whereby excessive sparking, at the contact points of a thennostat, due tointermlttent -and breaking of the circuit, is avoided.

contact is made the strength of the electric its normal strength by resistaficefso as to avoid excessive sparking at the thermostat "-h and will" then be automatically increased by shunting said resistance so as to throw the full strength of current into the circuit.

shown in t e accompanying drawin which is a representation or a form 'of e ectncal mechanism for operating thesteam valve is-Lshowrr'in section, and the electrical controlling .devices are shown diagrammatically.

The particular fdrl'n of valve operating mechanlsmywhich is. shown in the drawing but is morefully described-and c aimed in my 00- ending application filed January20,

' In the construction shown in the draw-' lngs, the steam valve 1 is in the form of an phragin bears upon ahead 3 at the upper end Specification ofLetters Patent. Application filed June 15, 1905. Serial .110. 265,399.

- 11 se arate Patented May 1 1-, 1909.

. The-passage between the casing 6 and said steam pressuredevice is controlled by means of Y the check valve 7, which is normally urged to its closed position by means of the spring-8. The steam-pressure device consists of a water reservoir 9\provided with an-electrical heater "10 for heating the water 1 contained'therein; The steam pressure detreservoir by the heater 1'0.

l from the reservoir 9 o ens the valve 7 and forces the diaphragm 2 ownward to'close the steam valve 1; When the heater 11 is E-operating after the steam in the reservoir 9 as become cooled and condensed, the check valve 7 is opened by means of the diaphragm 12 and the water above the dia hragm 2 runs back into the reservoir 9 an permits the springs to open the valve 1. e

The c rcuits for operating the heaters, are controlled by thermostatic. means which befhe'reinafte'r described, and are also con trolled by the water pressures of the valve operatin mechanism. These water pres- When the heater 10 is operating, the water normally urged by a spring 13 toward the po sures ma e .or break-the circuits at the 0011- I tact points 14, 15 and 16, through the action of Bourdon tubes .14, 15, and 16. The

tube 14 communicates with the interior of the water chamber of the heater 11 and the tubes 15 and 16 communicate with the compartment above the dia hragm 2.

The conductors of t e circuit which supplies current to the heater 10 are indicated by the reference letter C, and the conductors of the circuit which supplies current to the heater 11 are indicated by D. Where both reference letters are used the conductor, forms a part of each circuit. The electrical circuits are connected at L with a source of electricity.

1 The thermostatwhich controls the circuits C and Dlfccnsists of a movable member or arm '17, apair of contact points 18 and 1 9,

2'0 are indicate by the mitial letters land BY which are connected respectively with the circuits C and D, and a curved stripwhich v is'formed .of adjacent laminations of two diiferent metals I and 13,. which expand fdifieren'tiallyunder changes of temperature and thereby tend to increase or decrease the curvature of the strip 20 and shift the arm 17 between the contact" points 18 and 19. The' strip 20 is rigidly connected with a lever arm 21 which is pivoted at 22 and is adjustable about its pivotalv axis by means of an eccentric 23. The eccentric 23 is provided with. .a

pointer 24 which indicates on a dial 25 the temperature to which'the thermostat is set.;. This mechanism for adjusting t e arm 17 is 'well'known .in thermostats and need not be more fully described in this application. The metals which are commonly used in the construction of the-strip'20 are iron and brass and their res ective positions in the drawing On account of the. greater expansibility of brass under changes of temperature, thev strip 20 will tend to straighten out and cause acontact between the arm 17 and the contact point 18 when the tem' erature falls below the temperature to whic the indicator 24 is r the oont'actpoint 19, an electric current will set, and a contact will be made with the contact point 19 when the temperature rises above such setting. l a

In order that'a delicate contact be'tween the' arm 17 and the contact point 19 will cause a proper closure of the circuit C, the

. switch 265s arranged, to close automatically whe'n'fa' .current flows over the circuit (3 and complete a shunt path for the current. This also avoids sparking between the arm 17.:a'nd the contact point 19, due to a delicatecon-.- tactat that point-and due to fluctuations of' 40 the arm 17 under slight variations of temperature, and'to the small volume of current pass ing through the resistance. In the form of switch 26 which is shown in the, drawings the switch arm 27 is constructed of laminations of brass and iron similarly to the strip 20. The arm 27is rovided with heating coils 28 and 29 which orm parts-of the circuit C and serve to cause the arm 27 to move into contact with the contact points 30 and'31.

resistance coil'32 is connected to one end of the coil 28 and the other end of the'coil 28 is grounded on the arm 27. 'This furnishesa' path of high resistance in series with the contact point 19 and the arm 17. As soon as a contact is made between the arm 17 and --flow through the heating coil 28. I This current will be reduced tosuch an extent by the resistance 32 that little or no sparking-will take place at the contact point 19, even 9 though the contact be-Huncertam. The arm 27' when heated by the heating'coil 28 will be distorted and carry its :contact point 33 into contact with the spring contact point 30. This closes a shunt of the circuit C which maintains aflow of current throutgh the' coil28 65' the arm 27 indepen ent of anysubse uentfluctuation of the arm 17 which mightoccur.

before the contact bctween 31 and 35 is com-'- pleted. The current now'flowsthrough the conductor 34, the arm 27, the heating coil 28,- and the resistance .32. The arm '27 continues to fbend under the heating action .of the coil 28 and closes the circuitO at the contact p ints 35 and'31; This shunts out the coils 2 and 32, but brings the heating coil 29 into the circuit. The greater part of the resistance being thus shunted out, thecurrent in the circuit C is largely'increased. A' sim-ilar switch might 'be provided in; the circuit D, but with the valve mechanismshown' I do not consider this as necessary on account of the'small amount of power which is requi for operating the heater 11."

. lows: Assume that the parts of the valve and itssoperating mechanism are in the positions shown in". the drawing. The steamjvalv'e 1 The operation ofthe device shown'is as fol-' v is open andthe radiator tends to' raise the temperature'of the room. This riseiintem perature causes the'brass lamination of the iron lamination and moves t e garm 17 into contact with the contact pdint .19 closing the circuit C. 'Sparkingat 19:.Will be reduced to a minimum'by the resistance 28 and '32. The current then flows over the circuit C, heats the coil 28 and movesthe switch arm "strip 20 ,to expand morelra than the 27 into contact at 30. This brings the shunt 1 secondv heating coil '29. The heat devel-- oped within-this coil insures acontinuedv contact at 35 and 31.- The completion of the circuit' C causes a heating of thewater in the thus foi'med increases, water is forced through'the check valve 7 into the compartment above the diaphragm 2, forcin said' diaphragm down and closing the va W 1. The check valve 7 now returns to im. seat. Continiied increase in the pressure vof the steam in the reservoir 9 is communicated -through thee-heck valve 7] to the compartment above thediaphra m 2 and causes the v 'Bourdon tube 15 to brea thc'circuit C 'at 15; This pressure also "causest'he Bourdon tube 16 to form a c'ontact at 16;;- The. valve 1 is now in its closed ,positionand the water.

heater 10 and as the pressure of the steam broken, the heating effect of the coils 29 and as the valve 1 has'opened reduction of pres,

inbefore described;

'. atively high resistance connected in series g 2., In a thermostat, the combination of a sumesits normal position as shown in the the heater 11 to generate steam which forces the diaphragm 12 down and opens the check be engaged by said member for closing said circuit at a certain predetermined temperacircuit, a member connected with the other and away from said contact point through above the diaphragm 2v is confined within the casing 6 by means of the check valve 7. The steam in the heater 10 and the reservoir 9, being no longer heated, cools off and condenses and since the supply of steam was also cut ofl" from the radiator by the closing of the valve 1, the temperature of the room gradually falls. As soon as the circuit C has been 28 ceases and the switch arm 27 therefore swings away from its contact points and asdrawing. When the temperature of the room falls, the arm 17' of thethermostat swings into contact with thecontact point 18 and completes the circuit D.v This causes valve 7, thus releasing the pressure of the water above the diaphragm 2 and permitting the springs 5 to open the valve 1. As soon sure in the Bourdon tubes 15' and 16 breaks the circuit D and closes the circuit C at 15, so that the circuit C is again in condition for being completed through contact of the arm 17 with the contact point 19 as has been here What I claim as my invention and desire to secure by Letters Patent, is:- s

1. In a thermostat, the combination of a member adapted to move through 'temperature changes, an electric circuit having one terminal connected with said member and having a contact point suitably located to ture, a switch operated by the current in saidcircuit and adapted to shunt the current around said member and contact point, a relwith said switch, and means for automatically reducingthe resistance in series with said switch after an interval of time following the closing of said switch.

main circuit normally open, a contact'point connected with oneternnnal of said main terminal and adapted to be moved toward changes of temperature, a shunt circuit adapted to connect said terminals independently of the connection at said member and contact point, a switch controlling said shunt circuit, means operated by differential expansion of two substances under changes of temperature for controlling the opening and closing of said switch, a heating coil in series with said main circuit for o crating said means when said member is in e ectrical connection with said contact oint, and a second heating coil; adapted to old said switch r in its closed position regardless of fluctuai tions of said member.

3.-In a thermostat, the combination of a main circuit, normally open, a contact point connected withone terminal of said main circuit, a member connected with the other terminal and adapted to be moved toward and away from said contact point through changes of temperature, a shunt circuit adapted to. connectsaid 4 terminals independently of the connection of said member" and contact point, a heat-operated switch. controlling saidshunt Cll'CJllt, an electrical heater inse'ries with said main circuit adapted to close said switch when said member is v adapted to connect said terminals independently of the connection of said member and contact point,a heat-operated switch controlling said shunt circuit, an electrical heater in series with said main circuit adapted-to close said switch when said member is in electrical coiinectio with said contact point, an electrical heat r in sa d shunt circuit adapted to hold said switch in the closed said member andcontact point has been broken, and a second heat-o erated switch in said main circuit, adapte circuit through a rise in temperature.

5. A device of the class described comprising a circuit, athermostat arranged to open and close said circuit, resistance in series with said thermostat and adapted to prevent sparking at "the contacts of said to break said position after electrical connection between thermostat, a shunt in series with said resistance: but brid. u said thermostat con tacts, a. circuit c-osing device adapted toclose the circuit through said shunt through the closing of said. thermostat circuit, and

means operated through the closing of said shunt circuit for thereafter shunting out a substantial part of said resistance.

6. A device of the class described, comprising a circuit normally open, a thermostat adapted to close said circuit when exposed to a certain temperature,- resistance in series with the contacts of said thermostat, a nor mally open shunt in series with said resistance but bridging the thermostat contacts, and'means actuated through the closing of the circuit" through said thermostat and adapted to first close said shunt and afterward reduce the resistance of the circuit.

7. A device of the class described, comprising a circuit normally open, a thermostat adapted to close said c rcuit when ex osed to a certain temperature, resistance in series with the contacts of said thermostat, a normally open shunt in series with said resistance but bridging the thermostat contacts, and means actuated through the closing of the circuit through said thermostat and adapted to first close said shunt so as to include said resistance in series therewith and to afterward connect the same in parallel vfor successively reducing the resistance of the circuit.

8. A device of the class described, comprising a circuit normally open, a thermostat adapted to close said circuit when exposed to a certain temperature, resistance in series with the contactsof said thermostat, a normally open shunt bridging the thermostat contacts, a heating coil connected in series with the contacts of said thermostat, and a heat operated switch controlled by-said coil and .being adapted through a certain movement to close said shunt and to maintain the circuit independently of said thermostat and being adapted through a further movement to shunt out said resistance.

9. In combination with a thermostat, an anti-sparking device comprising a thermostat arm, a contact point arranged tobe engaged by said arm when the latter is flexed by heat, said armand point being connected in parallel'with saidthermostat, a heating coil carried by said arm for heating the same, said coil being in the circuit controlled by said thermostat, a second heating coil also carried by said arm and being normally on open circuit, and means actuated by contmued flexing of said arm for placing the second heating coil in arallel connection with the first heating coi and thus lowering the resistance in the circuit.

10. In combination with a thermostat, an anti-sparking device comprising a thermostat arm, a contact point arranged to be engaged by said arm when the latter is flexed by heat, said arm and oint' being connected in Lparallel with said t ermostat, a heating i 00' carried by said arm for heating the same,

said coil being in the circuit controlled by' said thermostat, additional resistance 'in Signed at Chicago this 12th day of 'June 190.5.

0 JOHN H. SWAN. Witnesses; I i

e E. A. RUMMLEii,

RUDo'w RUMMLER.-

series with said heating coil, a second heating 1 

